Method of forming glass to metal seals



Aug'. 2, 193s.

V. L. RONCl METHOD OF FORMING GLASS TO METAL SEALS Filed Feb. 4. 193e /NVENTOR u/Ro/vc/ Arron/vir Patented Aug. z, 193s l UNITED STATES PATENT. ori-ica l METHOD or FomvnNG GLASS 'ro METAL SEALs Victor L. Ronci, Brooklyn, N. Y., asslgnor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application February 4, 1936, serial No. 62,252

1 Claim.

utilized in speech transmission systems employing ultra-high frequency currents, a very high electrical efficiency must be maintained in order to enable satisfactory transmission of a wide `band of frequencies. 44Furthermore, the apparatus must have stability in operation so that the maintenance vcost will be low. 1n order to attain these results, the apparatus may be enclosed in an air-tight metallic container so that atmospheric conditions are ineffective to alter the characteristics of the apparatus. vThe terminal conductors on the container should form airtight seals with the container and also provide sufiicient insulation resistance to avoid current leak- .age and hence to prevent breakdown of the apparatus.

One object of thisinvention is to expedite and to reduce the cost of the production of efcient insulated terminal conductors for electrical apparatus.

In one illustrative embodiment of this invention, an insulated terminal conductor comprises a wire surrounded by a tubular metallic member or eyelet which supports the wire through the intermediary of a vitreous insulating spacer, such as a glass bead, fused to the wireand a flared end of the tubular member or eyelet.

lated terminal conductor is fabricated byv arrang- `ing the wire concentrically within the tubular member or eyelet with a short glass sleeve surrounding a portion of the wire and seated in the flared end of the tubular member. The glass sleeveis then heated so that it becomes plastic to form a bead which is simultaneously welded to the wire and the tubular member whereby an airtight seal is produced. In this method, it w'ill be apparent that the three elements, namely the wire, insulating member, and tubular member are fabricated into a unitary assembly in a single op-` eration s`o that an eillcient and effective airtight seal is produced in a manner readily adaptable to economical mass production by machine.

Y 'Ihe invention and the features thereof will be understood moreclearly and fully from the following detailed description with reference to the accompanying drawing in Iwhich:

Fig. 1 is an velevational view of anginsulated In accordance with this invention, the insuterminal conductor constructed in accordance with this invention;

Fig. 2 is another elevational view of the conductor shown in Fig. l-, partly in cross-section to illustrate the relation of the several elements 5 thereof;

Fig. 3 is afview in cross-section showing the relation of the elements of the conductor illustrated in Figs. l and 2, prior to the heating of the-vitreous element; 10

Fig. 4 is aside view, partly in cross-section, of an Yelectrical lter casing utilizing terminal convention;

Fig. 5 is an end view of the apparatus shown 15 in Fig. e illustrating the arrangement of the terminals therefor;

Fig. 6 is an enlarged detail'view in cross-section along `line 6-6 of Fig. 5;(and

Fig. 7' is a fragmentary view, partly in cross- 2c section, of a portion of an electron discharge device showing another application in which the terminal conductors constructed in accordance with this invention may be employed.

Referring now to the drawing, the terminal 25 conductor shown in Figs. 1 and 2 comprises a tubular metallic member or eyelet Iii, for example of copper, having a flared portion il machined to a knife edge at one end and a dished flange` I2 at the other end. A wire i3, for example of 3@ platinum or of the composition known as Cunife, is disposed centrally within the tubular member i0 and has sealed thereto a glass bead i4 which'is sealed'also to the flared por- In the fabrication of the conductor, as shownin Fig. 3, the wire i3 is held centrally within the tubular member or eyelet I0 by a tubular metallic spacer I5, one end of which is recessed as indicated at I6. The wire I3 is encompassed by a 4@ relatively thick glass sleeve I'l seated upon the flared end portion ll of the tubular member Iii. With the various elements in the position shown in Fig. 3, the sleeve I1 is heated so that it becomes plastic, flows about the `wire i3 and into 45 the recess I6, and welds to the wire I3 and the flared end portion Il to form airtight seals therewith. Th glass member, now in the form shown in Fig. 2, is allowed to cool and the spacer memvber I5 is then withdrawn.

. 'I'he glass sleeve I1 may be heated to render it plastic by a suitable flame'y or by `heating the tubularmember l0 byhigh frequency induction as described in my copending application, Serial No. 62,253, filed `February 4, 1938.

ductors constructed in accordance with this in- 'I'he terminal conductors constructed in accordance with this invention lmay be used to advantage in electrical apparatus such as a illter as shown in Figs. 4, 5 and 6. As illustrated in these ilgures, the iilter apparatus comprises a metallic container Il in which suitable condensers il, an inductance 20 and a crystal 2l, each provided with suitable leading in conductors 22. are mounted. The container Il is closed at one end by an integral plate and at the other endV by a cover I3 having flanges '24. The cover 23 is sealed to the container by a continuous nllet oi solder extending around the edge of the cover. The cover 2l is provided with integral arms 2i carrying an inner insulating block 26, and has mounted thereon an outer insulating block 21. The insulating block 3l may be aillxed to the cover 23 by a pair of screws 2l, one of which. as shown in Fig. 5, also holds a ground terminal 29 in position. As illustrated in Fig. 6, the insulating block 21 supports a plurality of bracketlike terminal members 30, each of which is se-I cured to the block by an eyelet Il and is held against rotation by a stud 3l forced into an aperture in the block 21.

The cover 23 carries also a plurality of terminal conductors constructed in accordance with this invention. which are disposed in alignment with the terminal members 30. The dished ilange i2 oi each oi the terminal conductors is seated in a troughed portion l! in the cover Il and amxed, as by soldering, tothe cover. One end of the wire Il of each terminal member, which may be encompassed by an insulating sleeve 34 fitted within the tubular member i0, is wound about and soldered to one end of the terminal member 3B as indicated at I5. 'Ihe other end ofthe wire Il extends through an aperture in the insulating block 26 and is wound about andA soldered to another terminal member I6 as indin cated at 31, the terminal member It being fastened to the block `2l as by` a bolt Il.

The cover 23 may be provided with a suitable inlet I! through which Adry air may be passed into the container il for the purpose oi ridding f the apparatus of moisture. The inlet may be sealed by a drop oi solder as shown at 4l.

Another advantageous application o! terminal conductors constructed in accordance with this invention is'illustraed in Fig. 'I wherein there isshown a portion o the enclosing vessel li of an all-metal electron discharge device in which an insulating member 42 is mounted within the vessel, which may serve as-the anode of the device,` and a illament II is supported by the insulatlng member '42. The terminal conductors are secured to the base of the vessel 4|, as by soldering the flange i2 thereto, and the wires l! connected to the illament 43 to serve as leading in conductors therefor. The insulating member 41 and illament may be inserted through the upper end of the vessel 4i and this end then closed by a cover or end plate 5i which may be welded to the container. li.

Although specific embodiments and applications of this invention have been shown and described, it will be understood, of course, that the invention is capable of a variety of other applications and that inodiilcations may be made therein. without departing from the scope and spirit V.thereof as defined in the appended claim.

What is claimed is: The method of fabricating an insulated terminal conductor which comprises forming a tu- .bular metallic eyelet with a flared end portion,

inserting a wire through said eyelet, inserting a cylindrical spacer member having a recessed end into said eyelet for holding said wire coaxial with said eyelet, positioning said spacer member so that said recessed end is within said eyelet and in proximity to said ilared end portion with the recess opening toward said ared end portion, sliding a glass sleeve about said wire and seating it in said flared end portion, heating said sleeve while said assembled eyelet, spacer member and wire are vertically disposed to render said sleeve sumciently plastic to iiow into intimate engagement with said wire, flared end portion and recessed end solely under the iniluence of gravitational forces, sealing the plastic glass simultaneously to said wire and said ared end portion, and withdrawing said spacer member.

VICTOR L. RONC'I. 

